The present invention relates to a headrest device intended for a chair, a seat or the like, which has a substantially vertical backrest, said device having an attachment part, by means of which it is to be attached to the backrest, preferably in a vertically adjustable manner, and a headrest, which is mounted on the attachment part.
The object of the present invention is to provide a headrest device, which in a simple manner is horizontally adjustable for adjustment to the user""s sitting position on a chair, a seat or the like. The aim is to increase the user""s comfort and, when the headrest device is used on a vehicle seat, to reduce the risk of whiplash injuries in case of collision.
According to the present invention, this object is achieved by means of a headrest device, which is of the kind stated by way of introduction and characterised in that the headrest is mounted on the attachment part by means of two link arms, which at one end are connected, pivotally about a substantially vertical pivot axis, to the attachment part and which at the other end are connected, hingedly about a substantially vertical axis, to a respective nut means threadingly engaged with a substantially horizontal screw means, which is turnably attached to the headrest and which is arranged, in turning, to synchronously displace the nut means in opposite directions along the screw means and thereby to pivot the link arms about their pivot axes to change the horizontal distance of the headrest from the attachment part.
Preferably, the two link arms each have at said one end a toothed segment, whose axis coincides with the pivot axis of the respective link arms, the link arms being interconnected by their toothed segments meshing with each other.
In a preferred embodiment, one of the nut means is left-hand threaded and the other nut means is right-hand threaded, and the screw means is left-hand threaded in the portion with which the left-hand threaded nut means is threadingly engaged and right-hand threaded in the portion with which the right-hand threaded nut means is threadingly engaged.
In a preferred embodiment, the screw means consists of two screw parts, which form an angle with each other and which are non-rotatably connected to each other by means of a joint coupling and of which one part comprises the left-hand threaded portion and the other part comprises the right-hand threaded portion.
Preferably, the screw means projects from the headrest with at least one end, and an operating knob for turning the screw means is attached to the projecting end.